Two piece cutting edge

ABSTRACT

A two part cutting edge structure for an earth moving unit includes a first or adapter part which is adapted to be removably secured to the earth moving unit and a second or cutting edge part which is adapted to be removably secured to the first part. Each of the parts is generally elongated and includes a longitudinally extending, generally flat bearing surface arranged in side-by-side relation, and the other longitudinal edge of the second part provides a cutting edge. The adapter part is provided with two or more spaced-apart sockets having upper and lower walls, and the cutting edge part includes rearwardly extending tab arms which are received in the socket and are engageable with the upper and lower socket walls to prevent rotation of the cutting edge part about the adapter part. The abutting bearing surfaces of the two parts provide resistance against thrust loading on the cutting edge part, and the tab arms and sockets provide resistance against beam loading on the cutting edge part.

United States Paten Hahn et a]. [4 1 Aug. 22, 1972 [54] TWO PIECE CUTTING EDGE 1,963,847 6/1934 Jersey ..37/141 R [72] Inventors: Frederick C. Hahn, Beaverton;

Ronald R. Miller, Portland, both of Greg.

[73] Assignee: Esco Corporation, Portland, Oreg.

[22] Filed: Aug. 13, 1970 [21] Appl. No.: 63,450

[52] US. Cl. ..37/141 R, 37/142 R [51] Int. Cl. ..E02f 9/28 [58] Field of Search..37/l4l R, 141 T, 142 R, 142 A [56] References Cited UNITED STATES PATENTS 3,497,973 3/1970 Campbell ..37/141 R 1,872,307 8/1932 Lehman ...37/141 T 3,126,654 3/ 1964 Eyolfson et a1. ..37/142 R 2,113,420 4/1938 Younie ..37/141 T 3,160,967 12/1964 Nichols ..37/141 T 1,772,624 8/1930 Brendlin ..37/141 R 2,482,320 9/1949 Clemmer ..37/141 R X 2,285,039 6/1942 Lowe ..37/141 R 3,478,449 11/1969 Baker ..37/141 R Primary Examiner-Edgar S. Burr Attorney-Dawson, Tilton, Fallon & Lungmus ABSTRACT A two part cutting edge structure for an earth moving unit includes a first or adapter part which is adapted to be removably secured to the earth moving unit and a second or cutting edge part which is adapted to be removably secured to the first part. Each of the parts is generally elongated and includes a longitudinally extending, generally flat bearing surface arranged in side-by-side relation, and the other longitudinal edge of the second part provides a cutting edge. The

adapter part is provided with two or more spacedapart socketshaving upper and lower walls, and the cutting edge part includes rearwardly extending tab arms which are received in the socket and are engageable with the upper and lower socket walls to prevent rotation of the cutting edge part about the adapter part. The abutting bearing surfaces of the two parts provide resistance against thrust loading on the cutting edge part, and the tab arms and sockets provide resistance against beam loading on the cutting edge part.

11 Claims, 15 Drawing Figures PATENTED M1822 r912 -3: G- FIG. I4 vs 67 74 1 \'VE.\'Z wk 5:

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sum 3 BF 3 L ;.\'\/'E;\ i 0R3. FREDERICK C. HAHN RONALD R. MILLER ATT YS TWO PIECE CUTTING EDGE BACKGROUND This invention relates to a cutting edge for an earth moving unit, and, more particularly, to a two piece cuttingedge assembly in which the cutting edge is securely mounted yet readily replaceable.

Earth moving equipment such as scrapers, bulldozers, dragline buckets, backhoes, shovel dippers, and the like are generally provided with a cutting edge which is adapted to engage and displace earth. Because the main digging unit, for example the bucket of a dragline, is relatively expensive, it is desirable to pro.- vide a replaceable cutting edge structure so that the cutting edge can be maintained relatively sharp without having to rework the entire bucket. The cutting edge must be securely mounted, however, to withstand the considerable forces which are exerted thereon during digging or scraping, and suitable securement is generally obtained only by sacrificing some degree of removability. Further, many so-called replaceable cutting edge parts become distorted under the extreme stresses encountered during digging, and replacement of the cutting edge is thereby rendered extremely difficult, resulting in considerable down time forthe earth moving unit.

SUMMARY The invention provides a two piece cutting edge structure which permits the cutting edge to be quickly replaced through mechanical locks, thereby eliminating excessive down time of the equipment which generally results when the cutting edge is attached by bolts or by welding. One part of the cutting edge structure is boltably secured to the digging unit, but this part seldom requires replacing. The second part of the structure provides the cutting edge, and this part is removably secured to the first part by a locking pin. Although the cutting edge part is readily removable from the first part, the parts cooperate in a unique manner to provide resistance against any type of force that is likely to be encountered during the digging operation.

DESCRIPTION OF THE DRAWING The invention will be explained in conjunction with an illustrative embodiment shown in the accompanying drawing, in which FIG. 1 is a fragmentary perspective view of an earth moving unit equipped with a two piece cutting edge formed in accordance with the invention;

FIG. 2 is an enlarged fragmentary perspective view of a portion of the cutting edge of FIG. 1;

FIG. 3 is a fragmentary top plan view of one part of the two piece cutting edge; 1

FIG. 4 is a top plan view of the other part of the two piece cutting edge;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4 with the arrows representing the external forces that could exist during operation;

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 3;

FIG. 7 is a view taken along the line 7-7 of FIG. 4 with the arrows representing the external forces that could exist during operation;

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 3;

FIG. 9 is a sectional view showing the interrelationship of the two parts of the cutting edge structure that would be seen along the lines 5-5 and 6-6 if the parts illustrated in FIGS. 3 and 4 were assembled;

FIG. 10 is a view showing the interrelationship of the assembled parts of FIG. 3 and FIG. 4 that would be seen along the lines 7-7 and 8-8;

FIG. 10A is a view similar to FIG. 10 of a modified form of the invention;

FIG. 11 is an enlarged elevational view of the locking pin shown in FIG. 9;

FIG. 12 is a top plan view of the locking pin taken along the line 12-12 of FIG. 11;

FIG. 13 is an enlarged elevational view of the pin lock member shown in FIG. 9; and v FIG. 14 is a top plan view of the lock member taken along the line 14-14 of FIG. 13.

DESCRIPTION or SPECIFIC'EMBODIMENT The invention will be explained in conjunction with a scraper blade designated generally by the numeral 20 in FIG. lwhich is provided as part of an earth moving vehicle 21 commonly used, for example, in the construction of roads. The invention is not limited to the cutting edge of scraper blades, however, and is applicable to almost any earth moving or digging equipment for which a replaceable cutting edge is desired. For example,the inventive two-piece cutting edge can be used as the router bit of a scraper, as the cutting edge of a bulldozer, as an adjustable side cutter on dragline buckets, backhoes and shovel dippers, as a replaceable lip for backhoes, draglines, shovel dippers, clamshell buckets, and on many other types of equipment where structural and wearlife capabilities are required in a digging tool comprising a lip and cutting edge assembly.

The scraper blade 20 includes a conventional moldboard 21, and a replaceable two-piece cutting edge assembly designated generally by the numeral 22. The cutting edge 22 is seen to include four cutting edge combinations22a, 22b, 22c and 22d arranged end-toend along the lip of the moldboard 21, and one of the cutting edge combinations is shown in FIG. 2. Each of the cutting edge combinations includes a first or adapter part 23 which is removably secured to the moldboard 21 by bolts 24 and one or more edge parts 25. The adapter part 23 is seen to have a generally elongated rectangular shape and includes longitudinal edges 26 and 27 and transverse side or end edges 28 and 29. Each edge part 25 also includes a pair of Iongitudinally extending edges 30 and 31 and a pair of transverse side or end edges or walls 32 and 33. In the particular embodiment illustrated, the edge parts 25 extend for about half the length of the adapter part 23 and are arranged in end-to-end relation on the front longitudinal edge 26 of the adapter part. The relative sizes of the parts 23 and 25 may be such, however, that the adapter part may receive one cutting edge part or three or more cutting edge parts.

Referring to FIG. 6, the adapter part 23 includes a flat bottom surface 34 which is bolted against the flat moldboard 21 by the bolts 24 and a contoured upper surface 35. The upper surface 35 extends generally parallel to the bottom surface 34 rearwardly to bolt holes 36 (FIG. 3) and then tapers downwardly toward the rear edge 27 to form a trailing edge portion of reduced thickness. The bolt holes 36 are preferably square for cooperation with a correspondingly shaped shank on the bolts 24, and the bolt openings may be countersunk as at 37 to receive the bolt heads.

The front of the adapter part 23 includes nose portion 38 of reduced thickness provided by downwardly and upwardly extending shoulders 39 and 40, respectively (FIG. 8), and upper and lower, generally parallel walls 41 and 42. The nose portion 38 terminates in a flat front surface 43. The shoulder 39 is interrupted at spaced-apart locations by recesses 44 which extend downwardly and rearwardly from the upper surface 35 of the adapter and terminate in socket portions 45 (FIG. 6) having upper and lower socket walls 46 and 47. Each recess also includes rearwardly extending side walls 48, downwardly and rearwardly sloping bottom wall 49, and rear wall 49a. The forward nose portion 38 of the adapter extends forwardly as at 38a between each pair of adjacent recesses 44 and is provided with a locking opening 50 aligned centrally with each recess 44 Each cutting edge part 25 includes a pair of rearwardly extending tab portions 51 adapted to be received in a pair of associated recesses 44, and the rearward longitudinal edge 31 of the cutting edge part is generally C-shaped as shown in FIGS. 7 and for cooperative engagement with the nose 38 of the adapter. Referring to FIG. 7, each cutting edge part 25 includes a generally rectangular body portion 25a having generally parallel top and bottom surfaces 52 and 53, respectively, and a reinforced or enthickened rear edge portion 54. The C-shaped rear edge of the cutting edge part is provided by inwardly extending upper and lower walls 55 and 56 and a generally flat wall 57 which extends forwardly at 57a to follow a contour generally the same as the forwardly extending nose portion 380 of the adapter part.

Referring to FIG. 5, each of the tab arms 51 includes a rearwardly extending major portion 58 having a flat bottom surface 58a and terminates in a tongue portion 59 which is spaced below the major portion 58 by offset connecting portion 60. The tongue portion lies generally on the transverse central axis xx of the cutting edge part and includes upper and lower surfaces 61 and 61a spaced equally from this centerline.

A locking opening 62 extends through each tab 51, and the opening is aligned with a lower opening 63 through the bottom portion of the C-shaped rear wall 31 of the cutting edge part. The bottom wall 56 of the rear edge includes a reinforcing rearward projection 64 adjacent the opening 63.

The two piece cutting edge structure is assembled by sliding the tabs 51 of each cutting edge part 25 into the recesses 44 in the adapter part 23. As the tabs are inserted into the recesses, the front nose portion 38 of the adapter is received in the C-shaped rear edge of the cutting edge part and the bearing surface 43 butts against the bearing surface 57 (FIG. 10). In this position, the tongue portion 59 of each tab is received in the correspondingly shaped socket portion of the associated recess, and the openings 62 and 63 in the cutting edge part are aligned with the openings in the adapter part. The rearward projections 64 of the cutting edge part are received in a correspondingly shaped recess 65 (FIGS. 3 and 6) in the shoulder 40 of the adapter part.

In the particular embodiment illustrated, the two parts are releasably locked together by a pin 67 and lock member 68 (FIG. 9). The pin and lock member are constructed in accordance with US. Pat. No. 3,126,654, issued Mar. 31, 19.64, to which reference may be had for details. Referring to FIGS. 11 and 12, the pin 67 includes a corrugated front surface 69 provided with recesses or notches 70, and a straight rear surface 71 provided with a central recess 72 which engages a correspondingly shaped projection 73 (FIG. 6) on the rear wall of the opening 50 in the adapter part. The lock member 68 includes a rubber body 74 which encases a pair of metal cylindrical inserts 75 which are adapted to be received in the recesses of the corrugated face of the locking pin.

Before the cutting edge and adapter parts are assembled, the locking member 68 is inserted in the opening 50 of the forward nose portion of the adapter part, and when the openings 62 and 63 in the cutting edge part are aligned with the openings 50 in the adapter part, the locking pin is driven through these openings into engagement with the metal inserts of the locking member. The locking pin can be inserted from either the top or the bottom of the cutting edge, and the resilient rubber body 74 of the locking member urges the recess 71 of the locking pin against the projection 72 on the adapter part and the rear. wall 71 against the flat rear walls 62a and 64a of the openings 62 and 64, respectively, of the cutting edge part.

FIGS. 5 and 7 show the external forces that could exist on the cutting edge part 25 during the operation of the earth moving unit on which the cutting edge assembly is mounted. These forces could be concentrated or distributed equally or non-uniformly along the front, top, and bottom of the cutting edge part, depending upon the material resistance to penetration in excavation and/or removal. For example, force A could exist at any angle in the upper left quadrant when the unit is in the normal digging and loading cycle. Force B of varying magnitude and angle could exist in the lower left quadrant when the unit is being dropped or initially penetrates the material to be excavated. Force C of varying magnitude and angle could be encountered when the unit is being removed or backed out of the material, and force D of varying magnitude and angle in the upper right quadrant could exist when the material is being removed from the rear containment area, such as when a bucket is dumpedor material is pushed out of a scraper. The combination of two or more of these forces could occur, depending upon variables during the operating cycle. For example, forces A and B could exist in the event the cutting edge was penetrating shale and a rock was encountered across the width or at some point on the cutting edge, thereby creating force B.

Using the laws of resolution of forces, either or any of these exterior loads can be broken down into horizontal and vertical components, which, in turn, are resisted by equal and opposite forces developed by the internal resistance of the assembly, and the two piece cutting edge structure has unique bearing and structural shapes which produce these internal reactions. Thus, force A can be broken into a horizontal component A and a vertical component A force B resolves into a horizontal component 3,, and a vertical component B force C provides a horizontal component C,, and a vertical component C,,; and force D provides a horizontal component D and a vertical component D Referring to FIG. 10, the horizontal or thrust forces A,, and/or B,, are resisted by like thrust forces in the opposite direction which are exerted by the flat load-bearing surface 43 of the adapter part on the flat bearing surface 57 of the cutting edge part. The flat surfaces 43 and 57 provide a butt contact or a substantially butt contact within the limits of economical manufacturing capability, and the thrust resisting force is normally distributed along the entire leading edge 38 of the adapter part outside of the forwardly extending portion 38a. Even if there is some initial clearance between thetwo load-bearing surfaces, the part will generally move by load force action or wear within a relatively short period of time into a butt contact.

The horizontal components of forces C and D are reacted by the resistance of the locking pin 67 (FIG. 9) to single or double shear at the points between the adapter part and the cutting edge part. Forces C and D are not likely to be as high in magnitude as forces A and B, since these forces are generally created by the backing up of the cutting edge from the material being penetrated, or by loose material which is being dumped. Accordingly, the resistance of the locking pin to shear usually will provide ample resistance to these forces.

The vertical force components A and D or the beam loading, are resisted by the upper surface 41 of the leading edge of the adapter part which bears against the upper surface 55 of the C-shaped rear edge of the cutting edge. Again, even if initial bearing does not occur between these surfaces, external forces will cause movement or preferential wear to occur to provide the bearing surfaces. Similarly, the vertical forces B and C, are resisted by the surface 42 which bears against the surface 56.

In the event that the forces A, and/or D, are relatively large, translation or rotation of the cutting edge part will occur to a point where the ends of the tab arms 51 engage the socket walls of the recesses 44. Referring to FIG. 9, counterclockwise rotation of the cutting edge part is resisted by the engagement of the socket wall 46 with the upper surface 61 of the rear end of the tab arm, and clockwise rotation of the cutting edge part is resisted by engagement of the bottom wall 47 0f the socket with the bottom wall 62 of the tab arm. It will be appreciated that the tab acts as a lever arm, thereby providing good capability to resist and dissipate these forces because of the mechanical advantage provided. A combination of forces A and B, or a combination of forces C and D, generally does not occur at the same time. However, in this event, the algebraic difference between the upward and downward external forces will be absorbed and resisted at the appropriate bearing surfaces between the tab arms and the sockets.

In the particular embodiment illustrated, the end portions of the leading edge 38 of the adapter part 23 are spaced rearwardly from the forwardly extending portions 38a adjacent the recesses, and the vertical surface 57 of the trailing edge of the cutting edge part is similarly contoured. This provides more wear material in the cutting edge part to account for typical wear patterns, which are generally higher at the joints of cutting edges due to the wearing tendencies of the material being dug and loaded. This higher force has a tendency to round the corners at these joints, and the additional wear material provides longer operating life. However, the thrust-resisting surfaces of the adapter and cutting edge parts could be straight if desired.

The beam load resisting faces 41 and 42 and and 56 of the adapter and cutting edge parts, respectively, are generally parallel to the center line x-x of the cutting edge part, and opposite faces are spaced about equidistant therefrom. In one embodiment the faces 55 and 56 diverged outwardly slightly, being spaced apart about 1.00 inch at the face 57 and about 1.06 inch at the rear edge 31 of the cutting edge part. The length of the faces between these points was about 0.69 inch. Similarly, the faces 41 and 42 were spaced apart about 1.00 inch adjacent the shoulders 39 and 40 and about 0.94 inch at the forward edge of the adapter.

The distance from the cutting edge to the thrust resisting face 57 was about 3.88 inch, and the distance from this face to the end of the tab arms was about 3.81 inch. The thickness of the tongue portion 59 of the tab arm was about 0.50 inch and the rear end was rounded on a radius of about 0.25 inch. The upper and lower socket walls 46 and 47 were spaced apart about 0.56 inch and the curved rear end of the socket had a radius of about 0.28 inch.

The cutting edge assembly can be provided in a variety of shapes to handle variable materials that are encountered in earth moving applications. For example, the invention can be applied to a clam shell lip where a tooth type or straight edge could be utilized to meet the digging and loading requirements while retaining the capability of quick changing the worn areas without the necessity of additional downtime for burning out lips and replacing them or for replacing bolted or welded adapters.

Also, by utilizing different lengths of replaceable cutting edge .parts, it is possible to provide a wide variety of complete assemblies to suit the variations in scraper design and width with a relatively small number of parts. The particular adapter parts 23 illustrated in FIGS. 1 and 2 have a length approximately twice as great as the length of the individual cutting edge parts, and the bolt holes 36 are spaced about 6 inches apart, with the bolt hole adjacent each side spaced about 2.88 inches from the side. A typical gap of about 0.25 inch occurs between adjacent adapter parts, so that the end bolt holes of adjacent adapter parts are also spaced about 6 inches apart. Accordingly, the length of the adapter part can be increased to receive three or even more cutting edge parts, or the length of the cutting edge part can be increased to the same length as that of the adapter part. For example, a typical adapter part for receiving two cutting edge parts may be 35.75 inches long with six bolt holes spaced 6 inches apart; a typical adapter part for receiving three cutting edge parts may be 53.75 inches long with nine bolt holes spaced 6 inches apart, and a typical adapter part for receiving one cutting edge partmay be 29.75 inches long with five bolt holes spaced 6 inches apart. The length of the cutting edge parts would, of course, vary depending upon the lengths of the adapter parts. By varying the sizes of the adapter parts, a cutting edge assembly can be provided for a variety of different lengths of scraper blades.

While we have described the generally C-shaped bearing surface as being located on the rear of the cutting edge part, this could be located on the adapter part and the nose portion which is received by the C- shaped edge could be on the cutting edge part. This can be seen in FIG. 10A in which the adapter part 23' is provided with a C-shaped forward edge, and the cutting edge part 25 is provided with a rear nose portion 38'. Further the tab arms and the sockets on the cutting edge and adapter parts, respectively, could be reversed so that the tab arms would be located on the adapter and received by recesses 'in the cutting edge part.

While in the foregoing specification, a detailed description of specific embodiments of our invention was set forth for the purpose of illustration, -it is to be understood that many of the details hereingiven may be varied considerably by those skilled in the art without departing from the spirit and scope of our invention.

We claim:

1. A two part cutting edge structure comprising an adaptor part adapted to be secured to an earth moving unit and a cutting edge part adapted to be releasably secured to the adaptor part and having afront cutting edge and a C-shaped rear edge provided by a first fiat wall and spaced-apart upper and lower flat walls which extend rearwardly from the first wall, the adaptor part having a flat front wall abutting the first flat wall of the cutting edge part and spaced-apart upper and lower walls extending rearwardly from the front wall and extending parallel to, respectively, the upper and lower flat walls of the cutting edge part, the adaptor part being provided with a socket spaced rearwardly of the front wall of the adaptor part and having upper and lower socket walls, the cutting edge part including tab means extending rearwardly beyond the C-shaped rear edge thereof and being received in the socket of the adaptor part between the upper and lower socket walls thereof to prevent relative rotation between the cutting edge part and the adaptor part, and locking means releasably securing the adaptor part and the cutting edge part together.

2. The structure of claim 1 in which the adaptor part includes spaced-apart upper and lower surfaces and the socket is provided through the upper surface of the adaptor part rearwardly of the flat front wall thereof and extends rearwardly between the upper and lower surfaces of the adaptor part to provide the upper and lower socket walls, the tab means including a first portion extending rearwardly from the cutting edge part above the flat front wall of the adaptor part and a second portion extending downwardly and rearwardly into the socket.

3. The structure of claim 2 in which the second portion of the tab means includes upper and lower surfaces extending adjacent, respectively, the upper and lower socket walls.

4. A two part cutting edge structure comprising an adaptor part adapted to be secured to an earth moving unit and a cutting edge part adapted to be releasably secured to the adaptor part, the adaptor part having a C-shaped front edge provided by a first flat wall and spaced-apart upper and lower flat walls which extend forwardly from the first flat wall, the adaptor part being provided with a socket spaced rearwardly of the front edge thereof and having upper and lower socket walls, the cutting edge part having a front cutting edge and a rear flat wall which abuts the first flat wall of the adaptor part and spaced-apart upper and lower flat walls which extend forwardly from the rear flat wall and which extend parallel to, respectively, the upper and lower flat walls of the adaptor part, the cutting edge part including tab means extending rearwardly beyond the rear wall thereof and being received in the socket of the adaptor part between the upper and lower socket walls thereof to prevent relative rotation between the cutting edge part and the adaptor part, and locking means releasably securing the adaptor part and the cutting edge part together.

5. The structure of claim 4 in which the adaptor part includes spaced-apart upper and lower surfaces and the socket is provided through the upper surface of the adaptor part rearwardly of the flat front wall thereof and extends rearwardly between the upper and lower surfaces of the adaptor part to provide the upper and lower socket walls, the tab means including a first portion extending rearwardly from the cutting edge part above the flat front wall of the adaptor part and a second portion extending downwardly and rearwardly into the socket.

6. A two part cutting edge structure comprising an adaptor part adapted to be secured to an earth moving unit and a cutting edge part adapted to be releasably secured to the adaptor part and having a front cutting edge and a rear flat wall, the adaptor part having upper and lower surfaces and a flat front wall abutting the flat rear wall of the cutting edge part, the adaptor being provided with a socket spaced rearwardly of the flat front wall thereof, the socket extending downwardly through the upper surface of the adaptor part and rearwardly between the upper and lower surfaces to provide spaced-apart upper and lower socket walls between the upper and lower surfaces, the cutting edge part including a tab arm having a first portion extending rearwardly above the abutting flat walls of the adaptor and cutting edge parts and a second portion extending downwardly and rearwardly into the socket between the upper and lower socket walls to prevent relative rotation between the cutting edge part and the adaptor part, and locking means releasably securing the adaptor part and the cutting edge part together.

7. The structure of claim 6 in which the second portion of the tab arm includes upper and lower surfaces extending adjacent, respectively, the upper and lower socket walls.

8. The structure of claim 6 in which each of the abutting flat walls includes a first portion-which extends below the tab arm and end portions, the first portion of each flat wall being spaced forwardly of the end portions thereof.

9. A cutting edge part adapted to be secured to an earth moving unit comprising a body having a front cutting edge and a flat rear wall adapted to abut a mounting member for the cutting edge part, upper and lower surfaces extending between the cutting edge and the rear wall, a pair of transversely extending end walls, and a tab arm having a first portion extending rearwardly from the body above the rear wall, a second portion extending downwardly from the first portion, and a third portion extending rearwardly from the second portion and being offset downwardly from the first portion by the second portion and being adapted to be received in a socket provided in a mounting member for the cutting edge part.

10. The cutting edge part of claim 7 including spaced-apart upper and lower flat walls extending rearwardly from the flat rear wall.

11. A mounting member adapted to mount a cutting edge part to an earth moving unit comprising an elongated body having upper and lower surfaces and a front edge portion, the edge portion having a flat front wall adapted to abut the cutting edge member, the mounting member being provided with a socket rearwardly of the flat front wall thereof, the socket extending downwardly and through the upper surface of the mounting member and rearwardly between the upper and lower surfaces to provide spaced-apart upper and lower socket walls between the upper and lower surfaces, the socket being adapted to receive an arm member of the cutting edge part.

UNITED STATES PATENT OFFICE CERTIFICATE OF CURREQTION Patent No. 3, 685,177 Dated August 22, 1972 Inventor(s) Frederick C. Hahn and Ronald R. Miller It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as'shown below:

Column 9, line 10 change 'claim 7" to claim 9 Signed and sealed, this 1 9th day of December 1972;

(SEAL) Attest: I EDWARD M.FLETCHER, JR. ROBERT GO'ITSCHALK Attesczing Officer 2 Commissioner of Patents 

1. A two part cutting edge structure comprising an adaptor part adapted to be secured to an earth moving unit and a cutting edge part adapted to be releasably secured to the adaptor part and having a front cutting edge and a C-shaped rear edge provided by a first flat wall and spaced-apart upper and lower flat walls which extend rearwardly from the first wall, the adaptor part having a flat front wall abutting the first flat wall of the cutting edge part and spaced-apart upper and lower walls extending rearwardly from the front wall and extending parallel to, respectively, the upper and lower flat walls of the cutting edge part, the adaptor part being provided with a socket spaced rearwardly of the front wall of the adaptor part and having upper and lower socket walls, the cutting edge part including tab means extending rearwardly beyond the C-shaped rear edge thereof and being received in the socket of the adaptor part between the upper and lower socket walls thereof to prevent relative rotation between the cutting edge part and the adaptor part, and locking means releasably securing the adaptor part and the cutting edge part together.
 2. The structure of claim 1 in which the adaptor part includes spaced-apart upper and lower surfaces and the socket is provided through the upper surface of the adaptor part rearwardly of the flat front wall thereof and extends rearwardly between the upper and lower surfaces of the adaptor part to provide the upper and lower socket walls, the tab means including a first portion extending rearwardly from the cutting edge part above the flat front wall of the adaptor part and a second portion extending downwardly and rearwardly into the socket.
 3. The structure of claim 2 in which the second portion of the tab means includes upper and lower surfaces extending adjacent, respectively, the upper and lower socket walls.
 4. A two part cutting edge structure comprising an adaptor part adapted to be secured to an earth moving unit and a cutting edge part adapted to be releasably secured to the adaptor part, the adaptor part having a C-shaped front edge provided by a first flat wall and spaced-apart upper and lower flat walls which extend forwardly from the first flat wall, the adaptor part being provided with a socket spaced rearwardly of the front edge thereof and having upper and lower socket walls, the cutting edge part having a front cutting edge and a rear flat wall which abuts the first flat wall of the adaptor part and spaced-apart upper and lower flat walls which extend forwardly from the rear flat wall and which extend parallel to, respectively, the upper and lower flat walls of the adaptor part, the cutting edge part including tab means extending rearwardly beyond the rear wall thereof and being received in the socket of the adaptor part between the upper and lower socket walls thereof to prevent relative rotation between the cutting edge part and the adaptor part, and locking means releasably securing the adaptor part and the cutting edge part together.
 5. The structure of claim 4 in which the adaptor part includes spaced-apart upper and lower surfaces and the socket is provided through the upper surface of the adaptor part rearwardly of the flat front wall thereof and extends rearwardly between the upper and lower surfaces of the adaptor part to provide the upper and lower socket walls, the tab means including a first portion extending rearwardly from the cutting edge part above the flat front wall of the adaptor part and a second portion extending downwardly and rearwardly into the socket.
 6. A two part cutting edge structure comprising an adaptor part adapted to be secured to an earth moving unit and a cutting edge part adapted to be releasably secured to the adaptor part and having a front cutting edge and a rear flat wall, the adaptor part having upper and lower surfaces and a flat front wall abutting the flat rear wall of the cutting edge part, the adaptor being provided with a socket spaced rearwardly of the flat front wall thereof, the socket extending downwardly through the upper surface of the adaptor part and rearwardly between the upper and lower surfaces to provide spaced-apart upper and lower socket walls between the upper and lower surfaces, the cutting edge part including a tab arm having a first portion extending rearwardly above the abutting flat walls of the adaptor and cutting edge parts and a second portion extending downwardly and rearwardly into the socket between the upper and lower socket walls to prevent relative rotation between the cutting edge part and the adaptor part, and locking means releasably securing the adaptor part and the cutting edge part together.
 7. The structure of claim 6 in which the second portion of the tab arm includes upper and lower surfaces extending adjacent, respectively, the upper and lower socket waLls.
 8. The structure of claim 6 in which each of the abutting flat walls includes a first portion which extends below the tab arm and end portions, the first portion of each flat wall being spaced forwardly of the end portions thereof.
 9. A cutting edge part adapted to be secured to an earth moving unit comprising a body having a front cutting edge and a flat rear wall adapted to abut a mounting member for the cutting edge part, upper and lower surfaces extending between the cutting edge and the rear wall, a pair of transversely extending end walls, and a tab arm having a first portion extending rearwardly from the body above the rear wall, a second portion extending downwardly from the first portion, and a third portion extending rearwardly from the second portion and being offset downwardly from the first portion by the second portion and being adapted to be received in a socket provided in a mounting member for the cutting edge part.
 10. The cutting edge part of claim 7 including spaced-apart upper and lower flat walls extending rearwardly from the flat rear wall.
 11. A mounting member adapted to mount a cutting edge part to an earth moving unit comprising an elongated body having upper and lower surfaces and a front edge portion, the edge portion having a flat front wall adapted to abut the cutting edge member, the mounting member being provided with a socket rearwardly of the flat front wall thereof, the socket extending downwardly and through the upper surface of the mounting member and rearwardly between the upper and lower surfaces to provide spaced-apart upper and lower socket walls between the upper and lower surfaces, the socket being adapted to receive an arm member of the cutting edge part. 